May 30, 2010

Space Lasers Could Help Predict Volcanic Ash Clouds

One thought to come out of a meeting of 50 experts gathered this week in Frascati is for Europe to require space-born lasers to help provide information on the vertical scale of volcanic ash clouds.

This information could be used to work out ash concentration levels, helping scientists determine the risk to aircraft engines.

Data from the U.S. Calipso lidar was shown to be very effective.

The European Space Agency currently has two lidar (light detection and ranging) missions in the works. ADM-Aeolus and Earthcare and planned to launch later this decade. Neither of the missions were driven by the need to monitor volcanic ash.

The Calipso spacecraft fires pluses of light into the atmosphere then catches the backscatter from particles. It can be used to effectively determine the thickness of drifting ash plumes.

If the vertical profile is combined with the plume, then a concentration can be calculated.

The airlines at this time are working with a very safe limit of four milligrams of ash for each cubic meter of air.

Dr. Ken Holmlund, the head of Eumetsat's meteorological observations division, said the necessity of space lidar instruments is sure to be featured in the paper.

"Esa will look into its future missions now to see if there is some tweaking that can be done or some additional instrumentation or further improvements that should be taken onboard," he told BBC News.

"And from a Eumetsat perspective, this really emphasizes the crucial role of the Meteosat Third Generation mission, which is now being debated. This was a clear message for me that for future volcanic monitoring, you really need good observations from geostationary orbit; and for Europe, it will be MTG or nothing."

The 3.5bn-euro MTG is one of Europe's flagship space endeavors. This craft will replace the current Second Generation spacecraft that returns 15-minute updates on the state of weather systems over Europe.

MTG will incorporate technologies like sensors capable of making highly detailed measurements in the infrared and ultraviolet/visible parts of the spectrum.

"Until now the data from the various missions have been used in isolation,". Holmlund told BBC News. "We should try more to look at multi-mission approaches, bringing together all the available data in a more effective way to make better products.

"What was demonstrated during this workshop was that the advice that has been given out by the VAACs has been very, very accurate in most cases; and this has been confirmed by aircraft measurements.

"There were a lot of [aircraft measurement] campaigns going out from France, the UK and Germany, and in most cases the ash was confirmed to be where the satellite data saw it and the modeling had predicted it to be. We did a pretty good job."